This invention relates to a support assembly for road vehicle wheels, and in particular to a support assembly for the drive wheels of motor vehicles.
A support assembly for motor vehicle wheels is known to usually comprise a hub for the wheels, a shaft, a spindle and a bearing with a structure which is very integrated with the rest of the mechanical members of the support, so as to reduce the number of necessary members and their weights, and to simplify the structure and construction of the wheel support assembly.
In a recent structural design, the rolling bearing of the drive wheels performs various functions, acting simultaneously as a hub for the wheels, as a bearing, as a shaft and as a spindle, by virtue of its special structure.
In this respect, the said bearing, which is usually of the mixed type consisting of two rows of oblique balls, comprises a substantially cylindrical inner race provided at one end with a flange for fixing to a vehicle wheel and with an inner surface in which a splined coupling is formed, and a substantially cylindrical outer race provided, at the opposite end to said end of the inner race, with a flange for fixing to the upright of a suspension for said wheel. The rolling bodies, slidable in suitable tracks, are disposed in the cavity lying between the inner race and outer race, and are isolated from the environment external to said cavity by means of known seal assemblies of the type consisting of a single or double sliding lip and a slinger shield, disposed between the inner race and outer race. By means of the splined coupling, the inner race is keyed on to a ball joint shaft, so enabling the torque to be transmitted to the wheel.
The described structural design is not without drawbacks. In particular, the need to transmit the torque from the ball joint to the wheel by way of the inner race of the bearing means that a very accurate splined coupling must be provided between the joint and the inner race, with consequent considerable machining difficulties and high cost. This is because very narrow tolerances are required, with perfect centering between the axis of the inner race and the axis of the splined coupling. In addition, the presence of the flanges on the opposite ends of the outer race and inner race makes it very difficult to insert the rolling bodies and to assemble the bearing, so making it necessary to limit the maximum number of rolling bodies which can be inserted. This means that the bearings must be over-sized in order to prevent overloading.